1. Field of the Invention
The present invention relates to an apparatus and method for the conversion of analog audio signals into digital data. More particularly, the invention is directed to an apparatus and a method for converting analog audio signals into digital data designed to provide a sound quality that is substantially the same as the original sound.
2. Description of the Related Art
With advancement of digital technology, various multimedia data are converted into a digital format for easy storage, archiving, and processing.
Quantization is a process of representing or converting an analog continuous signal into digital data, resulting in a quantization error. As the number of levels used for each sample increases during sampling in converting the analog audio signal into digital data, the digital data is a closer representation of the original sound.
Referring to FIG. 1, a general apparatus for converting an analog audio signal into digital data includes an input 10 into which an analog audio signal is input, an amplifier 20 that amplifies the input analog audio signal at a predetermined amplification ratio, a converter 30 that converts the amplified analog audio signal into digital data, a digital signal processor 40 that performs overall signal processing in order to store the created digital data, a storage unit 50 that stores the created digital data, and a reproducer 60 that reproduces the digital data stored in the storage unit 50.
The operation of the apparatus having the above-described configuration is described with reference to FIG. 2. Referring to FIG. 2, when an analog audio signal is input to the input 10 in step S1, the input analog audio signal is amplified by the amplifier 20 having a predetermined ratio of amplification in step S2. In step S3, the amplified analog audio signal is sent to the converter 30 that then converts the analog audio signal into digital data.
In step S4, the created digital data is sent to the digital signal processor 40 which then performs overall signal processing in order to store the digital data. In step S5, the digital data processed by the digital signal processor 40 is stored in the storage unit 50. Then, when reproducing a digital signal, the reproducer 60 extracts the digital signal stored in the storage unit 50.
In the apparatus for converting an analog audio signal into digital data, the amplifier 20 has a fixed amplification ratio that is sufficiently low to amplify an audio signal with large magnitude.
Thus, when the magnitude of a signal fed into the input 10 is small, a quantization error introduced by quantization is large compared to an actual audio signal. This quantization error causes the quantized signal to sound quite different from the original sound.